1. Field of the Invention
The present invention relates to a plug-in thermal diffuser for use with a substance to be thermally diffused, and more particularly to a plug-in device which provides a plug-through electrical connector and a thermal cutoff to neutralize the device in the event of overheating.
2. Description of the Related Art
Plug-in diffusers are well known in the art. In these devices, a resistance heater is disposed in a housing, out of which electrical prongs extend directly. When the prongs are plugged into a wall socket, the resistance heater generates heat. A substance, such as fragrance or an insect repellant, to be emitted into the air is maintained, either in liquid or solid form, in close proximity to the heater. As the heater heats the substance, controlled amounts are vaporized and emitted into the surrounding atmosphere.
These devices are particularly well suited to domestic use, especially in rooms such as kitchens and bathrooms, because they provide a continuous, controlled flow of desired substance into the air. However, these devices do require the use of a wall outlet, which are often in short supply in the rooms to which they are so well suited.
Also well-known in the art are plug-through electrical connectors such as adapters or extension cords having a conventional plug/socket construction. In these connectors, connector sockets are provided into which the prongs of an external plug are inserted, and connector prongs are provided for insertion into a wall socket. The connector provides an electrical "bridge" by which an external device to which the external plug is attached is electrically connected to the wall outlet circuitry. These connectors are used in wall-type outlets from AC power sources, as well as with various other power supplies, as an interface between integrated circuits, as adapters for use with any of the above, and in many other applications.
What has not been proposed in the art is a plug-in diffuser which includes a plug-through electrical connector. This combination device would permit the plug-in diffuser to be used without sacrificing a wall outlet, because an external plug could be connected to the wall outlet circuitry through the device itself.
A potential hazard with both the plug-in diffusers and the plug-through connector devices is the danger presented by faulty wiring or poor plug connections. These may result in increased temperatures, plastic deformation, or a fire. Attempts have been made to address problems associated with such wiring or connection problems by providing a thermal fuse mechanism which will cut off current flow in the event that the temperature of or current through a particular portion of a device rises above a certain threshold level.
For instance, U.S. Pat. No. 4,032,877, "Protector For Electric Circuits" to McAlister, discloses a temperature control protector. Disposed at either end of a tubular casing 12 of the protector is a ferrule-type metal terminal 14, 20 with an opening 18, 22. A cylindrical eyelet 24 extends into casing 12 from opening 22. An elongated current-conducting member 30 extends into the opening 18 of terminal 14 and fits into an opening 25 in the inner end of eyelet 24. Masses of heat-softenable alloy 38, 40 mechanically secure and electrically bond the ends of the current-conducting member 30 to the terminal 14 and the eyelet 24, respectively. If the temperature of the protector 10 rises above the softening temperature of the masses 38, 40, a helical compression spring moves the current conducting member 30 to open the circuit, and moves the head 32 thereof to a position indicating an open circuit. However, the protector in the '877 patent is not specifically designed for use with a plug-type device.
On the other hand, U.S. Pat. No. 4,275,374, "Fuse-Plug Adapter For Electrical Cord" to Chaucer, discusses a plug that includes a removable electrical fuse (not disclosed as being thermally triggered), in which a male element 1 extends from bottom opening 11a" toward a female element which is mounted in a first channel adjacent upper opening 11a'. Likewise, a male element 2 extends from an opening 11b" of a second channel, and a female element corresponding, but not continuous, thereto is located adjacent upper opening 11b'. The male element 2 and its corresponding female element each have a flange extending into the third channel. The male and female flanges contact, respectively, a lower fuse contact 12a and an upper fuse contact 12b of an electrical fuse 12. The fuse 12 is insertable and removable from the third channel through an insertion hole 6 at the bottom end face of the housing structure.
Neither of the foregoing devices provides a plug-in diffuser for use with a substance to be thermally diffused, and nothing in the art discloses or suggests such a plug-in diffuser which provides a plug-through mechanism whereby a separate appliance can be used in the same electrical outlet.
Also, none provides a mechanism for such a plug-through, plug-in diffuser whereby the full electrical current is neutralized in the event of overheating.
In addition, none provide any exterior manifestation of overheating in the event the current is neutralized by the thermal cutoff mechanism.
Accordingly, there is a need in the art for a plug-in diffuser for use with a substance to be thermally diffused, which provides a mechanism through which an external device can be plugged into the same electrical outlet.
There is also a need in the art for such a plug-in diffuser which interrupts the flow of electric current through the device using a thermal cutoff mechanism in the event of overheating.
There is an additional need for such a plug-in diffuser which will physically manifest the overheating in the event the thermal cutoff mechanism interrupts the flow of electrical current.